[Pacemaker] Corosync over DHCP IP

[Andrew Beekhof]

On Tue, Feb 12, 2013 at 3:09 AM, Dennis Jacobfeuerborn
<dennisml at conversis.de> wrote:
> On 02/11/2013 11:30 AM, Andrew Beekhof wrote:
>> On Mon, Feb 11, 2013 at 9:24 PM, Viacheslav Biriukov
>> <v.v.biriukov at gmail.com> wrote:
>>> It is VM in the OpenStack. So we can't use static IP.
>>> Right now investigating why interface become down.
>>
>> Even if you solve that, dynamic IP addresses are fundamentally
>> incompatible with cluster software.
>> You're effectively trying to create a cluster out of nodes which
>> change their name every time they boot.
>
> DHCP doesn't necessarily mean a dynamic IP.

In most (if not all) openstack deployments, it does.
Even better, the static IPs you can assign belong to the physical
hosts and don't show up inside the guests - so corosync can't bind to
them.

I actually tried to get a cluster _inside_ openstack working, but I
you'd need a particularly nice admin to change openstack's default
policies.

> In cloud environments the DHCP
> Server usually has a record in the leases database that associates a MAC
> address with an IP address so that the host will always get the same IP
> assigned.
>
> Regards,
>   Dennis
>
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